


Swapped

by Toonakan



Category: Undertale (Video Game)
Genre: Foncest, M/M, Past Abuse, Slow Burn
Language: English
Status: In-Progress
Published: 2016-06-21
Updated: 2016-06-21
Packaged: 2018-07-16 11:54:05
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,272
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7267084
Author URL: https://archiveofourown.org/users/Toonakan/pseuds/Toonakan
Summary: <blockquote class="userstuff">
              <p>Underfell Sans wakes up on the floor of his basement after making a deal with a person that should not exist only to find that it isn't actually his basement, or his house, or even his universe. </p>
<p>Usual Underswap/fell fic. I figured I'd give it a go.<br/>Any other pairings/characters/tags will be added as they come. </p>
<p>In this fic: Red swears A LOT</p>
            </blockquote>





	Swapped

He stared up at the plastered ceiling. An unimpressed grimace pulled at his normally grinning mouth as he lay flat on his back.

**_Well that was fucking anti-climatic._ **

Dull red peered upward from under a heavy brow and Sans let out a gruff snort.

**_Shoulda known the bastard would lie._ **

He wasn't entirely certain just how long it had been since he had come to, he'd gotten fed up of counting the wall clock's steady ticks quite quickly. Sans had at first woken with a sharp pain slicing through his skull which had kept him occupied for a short while, but it had receded into a dull throb as he had found himself too lethargic to make any sort of movement. His conversation with the creepy bastard had obviously been very draining for his soul. He'd have happily given into sleep, but something nagged at him to avoid it – that something wasn't entirely right – and so he'd ended up studying the flaking ceiling of his basement. Only now he was bored shitless.

**_Shoulda left the damn machine alone._ **

Sans glared upward, letting another snort escape his nasal cavity.

**_Boss is gonna be so fucking mad when he finds me._ **

Of course that was assuming that his brother would actually bother to look for him. Maybe Boss would be glad to be rid of his lazy good-for-nothing of an older brother. Sans knew his Boss was home, he had heard thudding footsteps from above accompanied by muffled shouts. No doubt Boss was screeching insults having noticed that Sans was missing from his post _again_.

It had gone quiet some time ago, but Sans let his eyes follow the sounds as the footsteps resumed again. They quickly paced toward here he assumed the front door would be. There was an almighty slam from above as his guess was confirmed. Boss had left the house, probably to run and check Grillby's for Sans. Boy he was gonna be pissed once he eventually found the shorter skeleton. Not that Sans could do much about it, he had pretty much been stuck spread eagled on the concrete floor of the basement the whole time.

A thought crossed his mind, fuck did the Boss even know how to get into the basement? It was the one place Sans would go to make sure that he was left alone. As far as he knew, Sans had the only key. Wouldn't stop his brother from trying to kick the sturdy metal door in though.

Sans flinched as said door swung open wildly, the metal echoing as it collided with the heavy brick wall.

**_Shit._ **

“Sans!” That was the Boss alright, though his voice sounded weird. It was less abrasive and more placid despite the panicked tone. Sans tensed up regardless. He was in for a beating. “Sans, are you down there buddy?!”

Sans did a double take, _'buddy'?_ No way in hell would his Boss use those kind of words. He tried to look toward the wooden stairway as it creaked under hasty feet. Turning his head even slightly caused a pang of nausea to settle in Sans's gut which elicited a low groan from the skeleton. Rolling his eyes this way and that, Sans was able to focus on the tall figure as they reached the base of the stairs. The guy certainly looked similar to his Boss, but what the hell was he wearing? Some stupid way too bright orange thing and baggy shorts. This guy wasn't Boss. Sans's Boss was way cooler than whoever this dumb-ass was.

“Bro you shouldn't be- _oh fuck!_ ” The fake Boss came rushing to Sans's side once he had noticed him, quietly muttering a string of obscenities to himself. Sans found himself now staring up at a much softer version of his Boss, for lack of a better word. Everything about his skull was far smoother, rounder and so much _weaker_ looking than his brother.

“Sans…?” The copy fell into a crouch and moved to run his phalanges across the part of Sans's skull that still defiantly throbbed.

The pain easily tripled as gentle bone slid across his brow. With almost a hiss, Sans lurched upward and away from the threat. His attempts to glare at the copy failed as a sickening vertigo caught Sans, making him wobble and fall down onto his knees. He caught the copy grimace as Sans retched, the strangled sound catching in his throat painfully. Something warm ran down Sans's forehead and began oozing into his right eye socket as he remained hunched over himself. It stained half of his vision crimson as Sans glared back up toward the copy.

He remained frozen in place, bony hands stretched slightly toward Sans with a look of confused worry plastered on his face. It was such a stupid expression Sans decided. The ooze in his socket began to overflow and dribble slowly down his cheek. With a grunt, Sans roughly wiped the back of a hand across his face. It came back a bloody red.

_**Ah fuck...** _

He wobbled again, forcing him to plant his other palm onto the ground so he wouldn't topple over completely. He had only just gotten off of the floor dammit.

“W-woah there buddy.” The copy came forward as though to catch him, bringing San's attention back to him. Sans backed away from the copy's reach.

“Don't you fucking touch me.” He growled lowly, continuing to shuffle backward until his back jostled the steel table behind him. His expression soured further as the copy let out a shakey chuckle.

“Well, you definitely aren't my little bro.” The comment made Sans bristle. He was too similar to the Boss, it was unnerving. He wanted the copy to leave.

“No I ain't now fuck off.”

“Jeez, I only want to help.” The copy looked a little hurt before inching forward slightly, hands raised in an attempt to appear non threatening. “My name is Papyrus. Who are you?”

What the actual fuck, now the copy was using his Boss's name? Sans growled as he slapped away an outstretched hand. His patience was wearing thin with the copy. Shame Sans still felt too worn out to dust the lanky fuck. Instead he enjoyed watching the friendly smile drop from the copy's dumb face before he opened his toothy mouth.

“Heh, no it ain't _buddy_.” Sans deliberately hung on the word, allowing his sharpened teeth to flash as a dangerous grin. “Don't you fucking use the Boss's name.”

'Papyrus' blinked slowly one, two, three times as though trying to process the situation. Sans watched warily, waiting for any signs that the copy was about to lash out. After all, Sans was at a disadvantage and-

“Nyeh heh heh...” The bastard was laughing to himself.

Sans grimaced, this guy was wrong in the head. The copy fell backward to sit on his feet, hands intentionally placed in his lap so that they remained visible to Sans.

“I think I know what's going on here.”

Sans snorted, “Yeah I'd really like to hear why the fuck you are in my basement.”

The copy gave him an almost sympathetic smile that made his gut twist. Something in the back of Sans' mind began to prod and pull in an uncomfortable manner. He knew, deep down Sans knew what the copy was about to tell him.

“About that buddy.” The copy scratched under his chin, appearing to be working out how to break the news. “I hate to be the bearer of bad news, but this isn't your home. If my theory is right, then this you don't even belong in this universe.”

**Author's Note:**

> Thankyou for your time. 
> 
> Feel free to kick me if I take too long updating, I procrastinate like a bitch.


End file.
